Better error message on GETINFO desc/* when you only have MDs.

The "GETINFO desc/id/OR identity" and "GETINFO desc/name/OR nick" options don't seem to work on the Tor control port:

GETINFO desc/id/DD397148A4AB4D43E5E6CB9C5F45E922872CC2D3 552 Unrecognized key "desc/id/DD397148A4AB4D43E5E6CB9C5F45E922872CC2D3"

If I replace "desc" with "md" I get the expected response, and they're both described in the spec as taking the same arguments...

Trac:
Username: mickeyc